I am sure a google could find you lots of info on generators. The larger expense will be the batteries and inverter. The more power you want to use overnight, the larger the bank of batteries you would need. Then, if you want to use conventional lights and TV's etc. you need an inverter and regulator.

Just to throw out some round numbers, it looks like a 400 watt generator can be had for a grand. A battery which stores 1KWH runs a couple hundred. ( 1kwh is the power consumed by a 100 watt light bulb burnig for 10 hours.)

Popular Science had an article in the last year or so about a ready to connect wind generator...supposedly installed for around $10K. One big enough to do justice may need to be high enough to get away from some ground effects and shielding from surrounding trees and other effects. Many places have a height limit in the local codes, so you need to overcome that hurdle first. Also, keep in mind that charging lead-acid batteries produces H2, which needs careful management or the house blows up...it is very difficult to see a hydrogen fire. Sometimes, it is just easier to hook it up to send back into the grid. It either slows your meter or reverses it if you are making excess. You can eliminate the battery bank unless you want it as an emergency backup rather than just a means to reduce your costs. Most if not all utilities have rules imposed on them where they have to buy your excess electricity. The rates may not be great, but it's better than nothing.

As I understand it, so far the PV's still need substantial rebates from utility companies and/or tax credits to be worthwhile in an economic sense. They can be competative for off grid installations where the cost of bringing in a service line is substantial.

The local utility started offering rebates so I've been browsing costs but not looking at the numbers real hard yet.

As I understand it, so far the PV's still need substantial rebates from utility companies and/or tax credits to be worthwhile in an economic sense. They can be competative for off grid installations where the cost of bringing in a service line is substantial.

The local utility started offering rebates so I've been browsing costs but not looking at the numbers real hard yet.

Click to expand...

It was THIS THREAD on a pool forum and his 10kv array that got me thinking about it.

Many areas have rules that require the utility to offer "net-metering" where you pay for the difference between what you produce and what you use. When you have demand exceeding production you draw from the grid; when you have production exceeding demand you "sell" to the grid.

If you look at your electric bill it will tell you how many kWHr you use. Lets say you use 720 kWHr in a month, or an average power of 1 kW. But wind power generally produces on the order of 25% of the rated power of the machine because of variation of available wind.

So you would need a 4 kW generator to produce and average of 1 kWHr.

If that 720 kWHr costs you $1000 per year, you might break even if you could get a 4 kW rated generator installed for $10,000 and you could depreciate it, maintain it, and pay the interest for 10% of the cost.

I think you would have a hard time achieving those numbers.

The government (that is all of us, via our taxes) pays 1.5 cents per kWHr subsidy to companies that produce wind power. That is why you see so many wind-farms in places that have wind.

We have an enormous windfarm nearby. Tourists are in awe and snap photos along the roadway. They think it's great that, thats how we power our homes
with wind turbines. WRONG.

Newsflash: The windfarm company sells it ALL to the grid. WE are stuck with all the windmills which many claim are eyesores. They also kill birds.

I'd would be OK with the adverse issues if I could take advantage of this power
but I can't, so I'm not.

And another thing---for anyone that thinks this is part of some cool green ecologic
thing. You can think again. The windfarm gets bought and sold to the highest corporate bidder now and then. Truth be known-they are actually almost as bad as the oil companies. They could care less...

You need enough battery to carry you through NO WIND periods, this can lead to a sizable investment, in addition sealed lead acid batteries have a usable life span of 3-5 years depending on number of discharges, depth of discharge and recharging current and times (should you start a recharge and then have a discharge). But wind coupled with solar may be viable, still need the battery, but between old sol and the wind the battery will see less discharges.

I think people that have any moderate sized system (wind, solar, probably not hydro) use non-sealed batteries. You can get some real monsters. You can get automatic rewatering caps.

The care and feeding of batteries is non-trivial. Modern electronics takes care of some of it. The larger percentage of full charge you remove the shorter the overall lifetime of the batteries. So you need a lot more capacity than you think. You can find numbers for this on the web. I am not positive but I think 50% discharge is a common limit.

Charging must be done carefully. Every so often the bank of batteries will need an "equalization" charge. They are charged to bubbling to bring all the cells to close to the same state. Each cell in a battery will have some variance from the others.

If you are serious about it you really need batteries designed for this service. For small systems lots of people use things like golf cart, marine, or fork lift batteries. Lead-acid is by far the most used type.

Batteries are designed and sized first on the type of discharge, for example short duration high current such as engine starting batteries or for power distribution longer duration low current such as you might use in a solar application. When purchasing batteries you determine you load (or expected load) and duration of support time you require. You need not concern yourself with. The manufactured data is based upon your expected shut down voltage, the lower the voltage you discharge a battery to the more capacity but this shortens life. For long duration discharges the typical shut off voltage of the system is 1.75 Volts per cell.

If you are serious about this get the PRPOER BATTERY for the application, the plates in a battery are designed for the particular application.

As for sealed versus flooded, the industry is moving away from flooded cells in smaller applications as there is less maintenance and handling of the open jars and off gassing is not as big an issue.